Unable to use import androidx.appcompat.widget.Toolbar into a java file when using AndroidJavaSource

[opcodewriter]

Android application type

.NET Android (net7.0-android, etc.)

Affected platform version

VS 2022 Version 17.6.5

Description

In my Android .NET 7 app, I have a java file where I'm trying to import Toolbar from androidx.appcompat.widget:

package androidapp5;

import androidx.appcompat.widget.Toolbar;

But it gives the following compilation error:

Severity	Code	Description	Project	File	Line	Suppression State
Error	JAVAC0000	 error: package androidx.appcompat.widget does not exist
import androidx.appcompat.widget.Toolbar;

This is the csproj:

  <Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net7.0-android</TargetFramework>
    <SupportedOSPlatformVersion>21</SupportedOSPlatformVersion>
    <OutputType>Exe</OutputType>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <ApplicationId>com.companyname.AndroidApp5</ApplicationId>
    <ApplicationVersion>1</ApplicationVersion>
    <ApplicationDisplayVersion>1.0</ApplicationDisplayVersion>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Xamarin.AndroidX.AppCompat" Version="1.6.1.3" />
  </ItemGroup>
</Project>

I also tried to manually add the following in the csproj but it didn't make any difference:

  <ItemGroup>
    <AndroidJavaSource Include="Interop.java" />
  </ItemGroup>

Note that when using the Toolbar class in C# code, it compiles OK:

using Toolbar = AndroidX.AppCompat.Widget.Toolbar;

namespace AndroidApp5
{
    [Activity(Label = "@string/app_name", MainLauncher = true)]
    public class MainActivity : Activity
    {
        protected override void OnCreate(Bundle? savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.activity_main);

            Toolbar toolbar;
        }
    }
}

Steps to Reproduce

Just create a Android .NET 7 app, add a file called Interop.java like above.

Here's the sample:

AndroidApp5.zip

Did you find any workaround?

No response

Relevant log output

No response

[moljac]

MacOSX

net8.0

dotnet build AndroidApp5/AndroidApp5.csproj /bl

output:

MSBuild version 17.7.0-preview-23251-02+59879b095 for .NET
  Determining projects to restore...
  Restored /Users/moljac/Downloads/12063900/AndroidApp5/AndroidApp5.csproj (in 686 ms).
/usr/local/share/dotnet/sdk/8.0.100-preview.4.23260.5/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.RuntimeIdentifierInference.targets(287,5): message NETSDK1057: You are using a preview version of .NET. See: https://aka.ms/dotnet-support-policy [/Users/moljac/Downloads/12063900/AndroidApp5/AndroidApp5.csproj]
/Users/moljac/Downloads/12063900/AndroidApp5/MainActivity.cs(15,21): warning CS0168: The variable 'toolbar' is declared but never used [/Users/moljac/Downloads/12063900/AndroidApp5/AndroidApp5.csproj]
  AndroidApp5 -> /Users/moljac/Downloads/12063900/AndroidApp5/bin/Debug/net7.0-android/AndroidApp5.dll

Build succeeded.

/Users/moljac/Downloads/12063900/AndroidApp5/MainActivity.cs(15,21): warning CS0168: The variable 'toolbar' is declared but never used [/Users/moljac/Downloads/12063900/AndroidApp5/AndroidApp5.csproj]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:00:53.47

msbuild.binlog.zip

[dellis1972]

Thanks for the repo app.

I have replicated the issue. There is a bug in the AndroidJavaSource support. It will work with basic java types, however it does have a problem when you try to reference .jar files which are extracted from NuGet packages.

In this case the androidx.appcompat has a classes.jar file, but it is inside an .aar file. This .aar file is extracted to the obj\Debug\net7.0-android\lp\ directory but these directories are NOT included in the list of file needed to compile the code in your .java file.

We will need to update our build system to include these files.

[opcodewriter]

@dellis1972 Thank you. Any timeline for the fix? Will it be fixed in .NET 7? Or is it already fixed in .NET 8?
I need this to work in .NET 7...

Any workaround at the moment?

[dellis1972]

@opcodewriter Its not fixed anywhere at this time. I'll need to figure out what needs to get fixed first.
It might make the final .net 8 release. I'm not sure if it will get ported back to .net 7.

I'll try adn figure out a work around for you

[dellis1972]

@opcodewriter

ok try adding this to your .csproj just above the final </Project> element.

  <Target Name="_WorkaroundRemoveMeAtSomePoint" BeforeTargets="_DetermineBindingJavaLibrariesToCompile" DependsOnTargets="_GetLibraryImports">
  </Target>

See if that fixes the issue.

[opcodewriter]

In the actual sample app, there's no more compilation error, but when I try to use it in some actual code, I get this error and many warnings:

Error	JAVAC0000	warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
  reason: class file for androidx.annotation.RestrictTo$Scope not found
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.TESTS
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.TESTS
warning: unknown enum constant Scope.TESTS
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant AnnotationRetention.BINARY
  reason: class file for kotlin.annotation.AnnotationRetention not found
warning: unknown enum constant AnnotationTarget.CLASS
  reason: class file for kotlin.annotation.AnnotationTarget not found
warning: unknown enum constant AnnotationTarget.PROPERTY
warning: unknown enum constant AnnotationTarget.LOCAL_VARIABLE
warning: unknown enum constant AnnotationTarget.VALUE_PARAMETER
warning: unknown enum constant AnnotationTarget.CONSTRUCTOR
warning: unknown enum constant AnnotationTarget.FUNCTION
warning: unknown enum constant AnnotationTarget.PROPERTY_GETTER
warning: unknown enum constant AnnotationTarget.PROPERTY_SETTER
warning: unknown enum constant AnnotationTarget.FILE
warning: unknown enum constant AnnotationTarget.TYPEALIAS
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
 **error: cannot access LifecycleOwner
		mainActivity.setContentView(activityLayoutId);**
  class file for androidx.lifecycle.LifecycleOwner not found
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX
warning: unknown enum constant Scope.LIBRARY_GROUP_PREFIX

public static void initMainActivity(AppCompatActivity mainActivity, int activityLayoutId, int toolbarId) {
		mainActivity.setContentView(activityLayoutId);
		
		Toolbar toolbar = (Toolbar)mainActivity.findViewById(toolbarId);
		 mainActivity.setSupportActionBar(toolbar);
	}

[moljac]

@opcodewriter

Try adding Xamarin.AndroidX.Annotation.Jvm package reference:

https://www.nuget.org/packages/Xamarin.AndroidX.Annotation.Jvm

dotnet/android-libraries#727

[opcodewriter]

same error and warnings. Note my actual code is in a Android .NET 7 library, not an app like in my sample, not sure if it matters.

[opcodewriter]

Is this going to be released in .NET 8?

Thanks.